To obtain an epoxy resin composition improved in heat resistance, toughness and mechanical strengths by mixing an epoxy resin with a specified polyphenol.
One (1)mol of a compound of formula I (wherein P is H or a 1-4C alkyl; and X is hydroxyl or an alkoxyl) is reacted with 3-60mol of a phenol at 20-200°C for 1-30hr in the presence of an acid catalyst to obtain a polyphenol (A) of formula II (wherein R is H, a halogen, a 1-8C alkyl, an aryl or an alkenyl. A solution of a mixture of 1 equivalent (in terms of the hydroxyl groups) of the polyphenol with 1-20mol of an epihalohydrin is reacted with 0.8-1.5mol, per mol (in terms of the hydroxyl groups of the polyphenol) of an alkali metal hydroxide at 20-120°C for 1-10hr to obtain an epoxy resin (B) of formula III (wherein G is glycidyl). Component A or B is mixed with 0.7-1.2 equivalents, per equivalent (in terms of the epoxy groups) of component B, of a curing agent, 0.1-0.5 pt.wt., per 100 pts.wt. epoxy resin, cure accelerator and 0-90wt.% inorganic filler.
KUBOKI KENICHI
HASEGAWA RYOICHI
